211 



Australia 



Myzorhynchus bancroftii N. master! 



A. stigmaticus P. atratipes 



N. annulipes 



Philippine Isles 

 M. pseudo-barbirostris N. philippinensis 



Seasonal Prevalence. — Few observations have 

 been made on this point. It would appear that 

 there is one simple explanation which, at least 

 in part, will account for the prevalence of a 

 particular species at a particular time, and its 

 appearance or disappearance at others. We have 

 already shewn how selective the Anophelinae are 

 in their choice of breeding- grounds, consequently, 

 if at any time, e.g., the dry season, a suitable 

 breeding- ground does not exist, a particular species 

 or genus of the Anophelinae may be absent. 



Thus we found in Nagpur (India, C.P.), during 

 the dry season, in those places where shallow 

 puddles had dried up, Mym. rossii was rare, but it 

 abounded wherever puddles still remained. Where 

 weedy lakes existed, Nyss. fuligmosus was common, 

 elsewhere rare. Now these conditions are directly 

 dependent on the rainy season, and where vast 

 areas of weedy swamp are formed during the rains, 

 then M. nigerrimus prevailed, to disappear when 

 the swamps dried up. In temperate climes, the 

 temperature is, no doubt, an important factor, the 

 onset of the cold weather causing a general hiber- 

 nation. We may quote the following observa- 

 tions : — 



Nyssorhynchus pvetoviensis. — This species first 

 appeared February lo, and gradually became 

 more prevalent, superseding the other common 



